The problem is that Outlook looks through all folders for unread emails which includes the SPAMfighter folder. You need to tell Outlook to not search the SPAMfighter folder for unread emails. To do this, please follow these steps:

Right click on "Unread mail" in the "Search Folders"Choose "Customize this search folder"Click on "Browse"Remove the checkmark from the top folder (normally Personal folders) and put a checkmark on all folders below the root folder except the SPAMfighter folder. Now it should not look in the SPAMfighter folder for unread emails.